Community Research and Development Information Service - CORDIS

Study of many-body phenomena in collisions of highly excited atoms, statistical physics of neural networks and related complex systems

Amorphous ferromagnetic films of Fe-Co-Ni-Si-B system have been for the first time synthesized by pulse laser deposition. Faraday effect in thin amorphous films has been investigated for the first time. Films of semimagnetic semiconductors CdMnTe on sapphire and glass substrates have been deposited using KrFexcimer laser. Quantum dots of CdMnTe, CdMnSe and PbMnI semimagnetic semiconductors have been deposited. Different optical and magnetic measurements have been performed. These results can be useful for developing new magnetic field sensors.

TiN, TiC, CNx and SiGe thin films were deposited and characterized with many different techniques. Vapor-phase oxidation was studied. Metals and semiconductors films have been used as the targets. These kind of films can find applications in microelectronics (diffusion barriers, high-temperature devices)and mechanical industry (hard films). A special separator for removing microparticles from plasma plume was realized. The velocity distribution function of atoms and ions in plasma generated during ablation of ceramics and reactive ablation of Ti in N2 was investigated.

Theoretical studies of the kinetics of compound formation under pulsed laser action of materials in reactive atmospheres have been performed. The"vapor-phase" model of laser-induced high temperature reactions can explain the recent experimental results. It was shown that the main channel of gas phasereaction for evaporated titanium in nitrogen is the endothermic reaction between titanium and molecular nitrogen with appearance of TiN and atomic nitrogen.

A model of formation of large-scale relief (LSR) under action of laser radiation on melted metal surface in presence and absence of extrinsic electric field hasbeen considered. A new interpretation of the mechanisms of initial stages of growth of periodical structures has been given and at the same time an explanation of the increasing of mean speed of LSR growth and changing of form of their height distribution under the action of extrinsic field by multipulse laser evaporationof target has been proposed.

In-situ investigations of the optical emission from the plasma produced by excimer laser ablation of semiconductor (Si, Ge and SiGe) and metal targets in vacuoand in ambient atmospheres were performed in order to correlate the plasma characteristics to the deposited film characteristics.

The Rayleigh-Taylor instability of a laser plume expanding into an ambient gas was studied. A three-dimensional gas dynamic computer code was constructed.

Energy transport in metals submitted to ultrashort laser pulses was examined. Two-temperature model with different electron and lattice temperatures wasdeveloped. Analytical solutions of the two-temperature model equations were obtained in particular cases. A computer program for the exact numerical solution of the two-temperature model was constructed.

Qualitative theoretical analysis of different physical mechanisms in UV-laser ablation of polyimide was done versus pulse length. This analysis establishes the reasonable correspondence with experimental data, and explain some results which seems to be in contradiction with conventional method ofanalysis.

It was shown that purely thermal ablation can accompanied by bulk process within the polymers. These processes lead to defect accumulation and (at someconditions) to carbonization effect in the laser-treated material. The existence of the second threshold related to multiple short and long pulse irradiation experiments has been demonstrated. It was shown that the effect of modification on the ablation kinetics qualitatively depends on the interrelation between activation energies of two considered bulk reactions.

The peculiarities of fast condensation and nanocluster formation within the expending vapor plume produced by ns laser ablation were analyzed theoretically.The generalization of Zeldovich-Raizer theory was done for inhomogeneous plume. The calculations were made for Si-vapor plume produced at typical conditions of excimer ns-laser ablation.

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D. SHERRINGTON
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Record Number: 22456 / Last updated on: 1999-05-24
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Collaboration sought: Information exchange/Training
Stage of development: Other